Nail Tek Hydration Therapy Surface Refining Ridgefiller Corrects Ridges and Nail Damage; Smoothes Nail Surface for Even Polish Application; Dries Quickly to a Matte Finish; Provides Superior Polish Retention. Surface Refining Ridgefiller corrects severe ridges for smooth, even polish application. Surface Refining Ridgefiller is designed to be applied over the appropriate clear strengthening formulation of HYDRATION THERAPY I, II, III, or IV so that polish appears smooth and flawless while nails continue to benefit from the strengthening and therapeutic properties of HYDRATION THERAPY.